1. Field of the Invention
The present invention generally relates to methods and systems for creating a recipe for a defect review process. Certain embodiments relate to creating a recipe for a defect review process based on inspection results for a specimen.
2. Description of the Related Art
The following description and examples are not admitted to be prior art by virtue of their inclusion in this section.
Inspection processes are used at various times during a semiconductor manufacturing process to detect defects on a specimen such as a reticle and a wafer. Inspection processes have always been an important part of fabricating semiconductor devices such as integrated circuits. However, as the dimensions of semiconductor devices decrease, inspection processes become even more important to the successful manufacture of acceptable semiconductor devices. For instance, as the dimensions of semiconductor devices decrease, detection of defects of decreasing size has become necessary since even relatively small defects may cause unwanted aberrations in the semiconductor devices. Accordingly, much work in the inspection field has been devoted to designing inspection systems that can detect defects having sizes that were previously negligible.
Another important part of yield control is determining the cause of the defects on the wafer or reticle such that the cause of the defects can be corrected to thereby reduce the number of defects on other wafers or reticles. Often, determining the cause of the defects involves identifying the defect type and other characteristics of the defects such as size, shape, composition, etc. Since inspection typically only involves detecting defects on the wafer or reticle and providing limited information about the defects such as location, number, and sometimes size, defect review is often used to determine more information about individual defects than that which can be determined from inspection results. For instance, a defect review tool may be used to revisit defects detected on a wafer or reticle and to examine the defects further in some manner either automatically or manually. Defect review can also be used to verify that defects detected by inspection are actual defects instead of, for example, noise and nuisance events.
Some examples of commonly used defect review tools include high resolution optical imaging systems, scanning electron microscopes and less commonly transmission electron microscopes. The effectiveness of the defect review process is determined, at least in part, by the parameters of the defect review process such as data acquisition parameters and/or data processing parameters. In particular, much like inspection processes, the data acquisition parameters and data processing parameters of a defect review process will have a profound effect on the defect review results. Therefore, it is important that defect review processes be performed with parameters that are suitable for the types of defects being reviewed and/or the type of layer on which the defects are being reviewed.
However, determining the appropriate parameters for defect review can be relatively time consuming and difficult particularly when the defect review tool has a large number of adjustable parameters and/or a large number of different defects are to be reviewed in a single process. In addition, a defect review process recipe is currently created manually by an applications or fab engineer. Therefore, such recipe creation is even more time consuming. For instance, an applications engineer or fab operator decides on the operating parameters for the defect review tool such as a scanning electron microscope (SEM) defect review tool and the inspection results needed to make those decisions. The number of operating parameters that need to be selected for the process may include about 10 or more parameters. Generally, operator time and training involved in setting-up or developing a recipe on a SEM defect review tool is no less than 20 minutes per recipe for the customer (e.g., on average more than 20 minutes per recipe, with recipe set up times varying from about 15 minutes for a relatively easy layer to several hours for a difficult layer).
Some foundries produce more than 300 recipes a year for an inspection tool (e.g., a brightfield optical inspection tool). Each of the 300 recipes may be designed for a particular wafer type and a particular layer of each wafer type. In turn, defects detected on each of those layers need to be reviewed, and each layer requires a different defect review process thereby resulting in more than 300 defect review process recipes needed each year. Manual recipe creation for such a number of defect review processes requires more than 100 hours of recipe setup time in a single year for the SEM defect review tool alone. Therefore, recipe setup by fab operators significantly reduces valuable time during which the operators could be solving problems or performing other yield-related functions.
Furthermore, once a defect review process recipe is created, the applications engineer or fab operator can save the manually selected parameters for the process. The applications engineer or fab operator also saves the process parameters with the name of the layer type that they were created to be used upon. For instance, the recipe for a layer formed of copper (Cu) after a chemical mechanical polishing (CMP) process may be saved as the Cu-CMP recipe. In addition, a recipe for a specific layer type must be manually selected by a process operator on the defect review tool for every lot or batch of specimens run for that layer type (on a wafer or reticle). Therefore, this operator needs to know the recipe name for the specific layer type; otherwise, an incorrect recipe selected by the operator will not find the inspected defects and defect review will not be performed successfully.
Accordingly, it may be advantageous to develop methods and systems for creating a recipe for a defect review process automatically without human interaction/intervention for all of the different types of specimens on which defect review is to be performed thereby providing quicker recipe creation, increased throughput and productivity, higher profits, lower probability for human error, and more effective defect review process recipes.